1. Field of the Invention
This invention relates to a video tape recorder (VTR), and more particularly to a two-channel (2ch) VTR which records a video signal separated into two channel components on a magnetic tape and reproducing the recorded signal.
2. Description of the Prior Art
Conventional 2ch VTRs widely used for broadcasting record video signals on a magnetic tape via two pairs of rotary heads in such a manner that a frequency modulated (FM) luminance signal Y and an FM chrominance signal C are recorded on separate tracks which are arranged alternately in the order of Y, C, Y, C, Y, C. The FM chrominance signal is a signal which is obtained by time-base-compression-multiplexing two chrominance difference signals and frequency-modulating the multiplexed signal, or a signal which is obtained by frequency modulating two chrominance difference signals with different carrier frequencies and mixing the frequency-modulated signals (a so-called frequency-division-multiplexed signal), or a signal which is obtained by frequency-modulating so-called line sequential chrominance difference signals which appear alternately at a cycle of one horizontal scanning period, or other types of signals. These are shown in Japanese Laid-Open Patent Application (Kokai) Nos. 59-4279, 59-34785, 58-131885, 59-104886 and 59-104887. Each pair of heads are disposed to be apart by 180.degree. from each other on a circumference of a rotary cylinder. Each head of each pair is disposed adjacent to one head of the other pair. A typical conventional 2ch VTR is shown in "A 1/2 INCH METAL-CASSETTE VTR SYSTEM" by S. Matsuda et al., Technical Report of the Institute of Television Engineers of Japan, Vol. 9, No. 2 (May, 1985), pp. 19-24.
Although the conventional 2ch VTRs can provide high quality video signals, they have the following disadvantages.
The conventional 2ch VTRs operate in only one fixed operation mode, i.e., standard mode, but cannot operate in special operation modes such as a long play mode. If they were required to operate in an additional operation mode, two additional two pairs of heads would have to be provided on the rotary cylinder, which would be very difficult or almost impossible.
Furthermore, the conventional 2ch VTRs, when recording, provide a guard band between each two adjacent signal tracks on the magnetic tape for eliminating crosstalk between the signals recorded on the adjacent signal tracks. This is disadvantageous for increasing recording density.
Furthermore, since two heads are disposed adjacent to each other, production and adjustment of the head system is very difficult, and a shield plate must be provided between two adjacent two heads for eliminating crosstalk between two adjacent two-heads. As the result, the head system of the conventional 2ch VTRs is too expensive to be applied to home use. This is the main reason that the 2ch VTRs have been used only for broadcasting.